@nestjs/common/decorators/core/optional.decorator.js

Nest - modern, fast, powerful node.js web framework (@common)

import { OPTIONAL_DEPS_METADATA, OPTIONAL_PROPERTY_DEPS_METADATA, } from '../../constants.js';
import { isUndefined } from '../../utils/shared.utils.js';
/**
 * Parameter decorator for an injected dependency marking the
 * dependency as optional.
 *
 * For example:
 * ```typescript
 * constructor(@Optional() @Inject('HTTP_OPTIONS')private readonly httpClient: T) {}
 * ```
 *
 * @see [Optional providers](https://docs.nestjs.com/providers#optional-providers)
 *
 * @publicApi
 */
export function Optional() {
    return (target, key, index) => {
        if (!isUndefined(index)) {
            const args = Reflect.getOwnMetadata(OPTIONAL_DEPS_METADATA, target) || [];
            Reflect.defineMetadata(OPTIONAL_DEPS_METADATA, [...args, index], target);
            return;
        }
        const properties = Reflect.getOwnMetadata(OPTIONAL_PROPERTY_DEPS_METADATA, target.constructor) || [];
        Reflect.defineMetadata(OPTIONAL_PROPERTY_DEPS_METADATA, [...properties, key], target.constructor);
    };
}